Simples Assim

• [MP4] is most commonly used to store digital video and digital audio streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images.
• The most widely-supported codecs are MPEG-4 Part 10 (also known as H.264/MPEG-4 AVC) for video and Advanced Audio Coding (AAC – MPEG-4 Part 3 Subpart 4) for audio.
• Codec designers should register the codes they invent, but the registration is not mandatory.

http://en.wikipedia.org/wiki/Mp4

http://www.mp4ra.org/